ORIGIN OF PHOSPHORTS COMPOUNDS IX HENS' EGGS 277 



We detormined tho phosphoi'us contont of a known fraction of tlio inorganic 

 phosphate soUilion ohiainod in Iho aV)ovo <lr>s(!ribo(l proeoduros V)y tho colorimol ric 

 motliod of FisKE and Subakow. The pliospliato content o\' another fraction of the 

 phosphate solution was precipitated in the form of ammonium magnesium phos- 

 phate and its activity determined by making use of a Geiger tube counter. L(>t 

 us say wo have administered a hen a hibelled phospliate sohit ion containing 1 mgm 

 P and showing an acti\'ity of lO^ counts per niinut(\ Wo want to know what per- 

 cent age of this labelled phosphorus will be found in tho yolk lecithin. To arrive 

 at this figure we take from our solution containing the labelled phosphorus as 

 much as corresponds to Vioooo ^^ ^^^ amount administered to the hen and preci- 

 pitate the phosphate, denoting the piecijjitate obtained as our standard preparation, 

 while wo will call tho precipitate obtained from the yolk lecnthin as leciithin prepa- 

 ration. Before precipitating both the standard and the lecithin preparation we 

 add to llie solution a known amount, usually about 80 mgm, of ina(!tive sodium 

 phosphate, by so doing we diminish the amount of labelled phosphate possibly 

 remaining in solution after precipitating with tho magnesium citrate reagents 

 and furthermore we obtain a standard and a lecithin preparation of equal weight. 

 The ^-rays emitted by the active phosphorus being to an equal extent absorbed 

 in the two preparations the activity of which is to be compared, their weight 

 and thus the thickness of the layers investigated being the same, there is no need 

 to pay attention to the absoibtion of the /3-rays in the samples investigated. Nor 

 need the decay of the radioactive P be considered, as both the prepaiations to be 

 compared, the lecithin and the standard preparation, decay at the same rate. 

 The yolk residue obtained after removal of the lecithin was treated in similar 

 way and also the white of the egg, while the shell was ignited and dissolved after 

 ignition in hydrochloric acid, the solution being tieated in the way described above. 

 Tho samples were placed in small aluminium dishes having a surface area of 1.1 cm^ 

 and were placed inunediately below tho aluminium window of the Geiger-counter 

 used. 



Befoie discussing the results obtained we recall some facts about the circulation 

 of labelled phosphorus in the blood. 



Sensitivity of labelling 



Let us start from labelled sodium phosphate preparation of such activity that 

 when the later was fii"st put into the blood, I mgm P will show 10000 activity 

 units. As a result of a rapid exchange going on chiefly between bone phosphate 

 and the inorganic phosphate of the blood 1 mgm will soon correspond to loss 

 than 10000 activity units. The total inorganics phosphate content of the blood 

 remains (constant, except in the case which wo will not consider at present where 

 a comparatively large amount is injected, while the individual phosphate ions 

 will very soon be replaced to a large extent by other phosphate ions which were 

 hitherto located in the skeleton or in other organs. After some time we shall find 

 a large part of the labelled phosphate in the organs and the probaliility that the 

 labelled phosphate leaves tho organs and gets back again into the blood will 

 increase, the effect of this re-entrance into the blood will be that with increasing 

 time the net rate of decrease of the inorganic labelled phosphate content of the 

 blood will be less and loss. Loss of phosphate by excretion and by the formation 

 of organic phosphorus compounds in the V)lood and in the oigaiis will fuithcr 

 complicate the curve representing tho labelled P contont of the blood as a function 

 of time. We determined tho latt(>r experimentally for the blood of different ani- 

 mals and also of human subjects, but not for tho hen, (Compare, however, the 

 results given on page 281). The conclusions drawn in this paper do not necessitate 



